While regulators, wastewater plant operators, hydroelectric managers and natural resource advocates argue about who needs to invest in cleaning up the Blackstone, one thing is clear: multiple factors contribute to the river's impairment. Multiple approaches are needed to clean it up.

To make the waterway truly fishable and swimmable, river advocates and those who discharge into it are calling for a more holistic approach to cleaning it.

“What we're really trying to do is manage these systems sustainably,” said Timothy J. Downs, chairman and associate professor of the environmental science and policy graduate program at Clark University.

“Where is phosphorus coming from? Stormwater and wastewater from an urban area,” he said. “How do we reduce the sources of the phosphorus the Blackstone (sewage plant) is being asked to treat? It's a more efficient way to solve the problem: source reduction.”

Mr. Downs said Worcester's aging sewer and stormwater systems are inadequate. Combined with the large amount of paved surfaces that prevent stormwater from being filtered in the ground, a notable amount of polluted runoff ends up in the river. The runoff carries nutrients from fertilizer and animal waste, bacteria and toxic substances such as motor oil.

The U.S. Environmental Protection Agency, which issues wastewater discharge permits for sewage plants, also issues permits to control stormwater runoff. They are called MS4 permits, which stands for municipal separate storm sewer systems.

The six minimum control measures under the MS4 permit issued in 2003 for small communities in the Blackstone watershed include public education and outreach; public participation; illicit discharge detection and elimination; construction site runoff control; post-construction site runoff control; and pollution prevention, such as street sweeping and catch-basin cleaning.

The draft permit issued in 2010 for small MS4 communities includes requirements to map and test outfalls to the waterway, among other actions.

Worcester is facing a new MS4 stormwater permit as well, which was released as a draft in 2008.

Earlier this year the EPA launched a voluntary program to integrate municipal planning for stormwater and wastewater control.

“There might be a benefit for municipalities to present to us all of their needs so we can prioritize where limited dollars can be spent,” said Michael D. Wagner, senior enforcement counsel for EPA's New England region.

In other words, if a city needs to upgrade its sewage plant and its stormwater system to meet EPA requirements, it could have more time to carry out the work in a way that makes sense.

No community has submitted a proposal for integrated stormwater/wastewater management yet, so it's not certain how practical the strategy will be.

“The future is unknown. The future is, I think, a lot of happy talk out of EPA,” said Robert L. Moylan Jr., Worcester commissioner of public works and parks and chairman of the Upper Blackstone Water Pollution Abatement District.

“The idea of integrated planning is a wonderful one. It makes eminent sense. I just don't think EPA is serious about that,” he said.

Others are more hopeful. The new integrated format “gets permits out of the silos,” according to Donna M. Williams, watershed advocate for the Blackstone River Coalition and chairwoman of the nonprofit Blackstone River Valley National Heritage Corridor Inc.

“We environmentalists think this is the way to move forward.”

Elizabeth Scott, deputy chief of surface water protection for the R.I. Department of Environmental Management's Office of Water Resources, said, “Our studies have shown the wastewater treatment facilities have been identified as the biggest sources of nutrients to the river.

“Nutrients are not the only thing wrong with this river. There's also bacteria and metal impairment. There really does need to be a holistic look at this river.”

Stormwater, wastewater and drinking water management comprise a “three-legged stool” needed to protect environmental and public health, Ms. Scott said.

As the river's restoration struggles forward, a new use for the historic waterway is cropping up: recreation.

Donald Martin, co-owner of Blackstone Valley Outfitters in Lincoln, R.I., has had customers from all over the world rent kayaks and bikes or fish in the trout-stocked river.

“They're looking for the solitude; they're looking for the quiet. And the quick water, too, — we take them on some whitewater,” Mr. Martin said.

He acknowledged that portions of the river still need cleaning up. Debris has accumulated behind dams, and the weedy growth in areas like Uxbridge's Rice City Pond can make paddling tough going.

Despite visible remnants of the Blackstone's heavy use, one family from South Africa, who took an evening kayak tour, told Mr. Martin, “We've paddled a lot of places and this is the most beautiful river we've ever been in.”

Mr. Martin said that after the 48-mile bikeway along the river is completed, recreation and related businesses should take off more.

“They're starting to find the Blackstone has a lot to offer,” he said.

Annual events along the Blackstone such as the Greenway Challenge adventure race and the Blackstone River Watershed Association's canoe and kayak race continue to grow in popularity.

Mr. Downs said that cleaning the Blackstone offers an opportunity for the whole community to understand the impacts of human activity on a critical natural resource. And solutions work best when everyone has a stake in the outcome.

“It all comes back to the central question of what do we want the Blackstone to look like 10, 15 or 20 years from now,” he said.

“What are the alternative futures for the Blackstone? What do we have to do?”